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Observing Overheads

Entrance Window

T-ReCS contains three entrance windows that are interchangeable in real time; the control software selects the window that is best for the specific observation and conditions.

T-ReCS Slits and Occulting Bar

T-ReCS contains 7 slit masks for spectroscopy, plus an "open" mask and an occulting bar for imaging mode. The slit widths are chosen to match the lambda/D and 2*lambda/D conditions at the upper end of the 10 and 20 µm wavelength bands, plus the lambda/D condition at three additional wavelengths in the 10 µm band. The lambda/D slits will generally provide the best spectral resolution in good seeing; the 2*lambda/D slits may be better in poor seeing or for fainter sources.

T-ReCS Diffraction Gratings

T-ReCS contains three diffraction gratings and an optical flat mounted on a rotating turret. Each diffraction grating is used in first order.

Filters

T-ReCS contains up to 20 filters mounted in two wheels. This page describes the current set of filters.

Detector Information

T-ReCS contains the same detector as Michelle . Some basic characteristics of the detectors are shown in the table below:

Entrance Windows

T-ReCS contains three entrance windows that are interchangeable in real time; the control software selects the window that is best for the specific observation and conditions.

Detector Information

T-ReCS contains the same detector as Michelle . Some basic characteristics of the detectors are shown in the table below:

Imaging

Basic characteristics of T-ReCS's imaging mode

T-ReCS is capable of imaging in the 8–26 micron range as follows:


  • Broad-band (N, Q) and Narrow-band Filter Imaging
  • Pixel size = 0.09" (fixed)
  • Field of view = 28.8"×21.6"
  • Number of filters: currently 20, capacity for 24
  • Occulting bar available for imaging (2" wide)

The principal T-ReCS imaging modes, plus the typical settings of five instrument components in each mode, are listed in the following table.

Sensitivity and Overheads

This section contains information on the sensitivity and performance of T-ReCS in its various observing modes. Go directly to:


  Initial Setup Observing efficiency
Imaging 6 mins 30%
Spectroscopy (chop-nod mode)